MONTREAL, May 10 (Reuters) - WestJet Airlines pilots voted on Thursday in favor of staging a possible strike, although they agreed to avoid any disruptive job action during Canada’s busy Victoria Day holiday weekend starting May 19, their union said in a statement.

WestJet pilots voted 91 percent in support of a mandate for a strike or lawful job action, as their union, the Air Line Pilots Association (ALPA), negotiates a first contract with Canada’s No. 2 carrier.

ALPA said the pilots, who remain at odds with WestJet on compensation, working conditions and job security, preferred to reach a negotiated deal and “not to strike.”

Earlier this week, WestJet said uncertainty from the labor dispute, as passengers deferred travel bookings, along with higher expenses, would weigh on second-quarter earnings, sending shares to their lowest point in two years.

WestJet Airlines Chief Executive Ed Sims has said he aimed to reach a first agreement with unionized pilots this year.

“We respect the outcome of this vote and recognize the mandate WestJet pilots have given ALPA,” Sims said in a statement. “We are certain our guests will appreciate that this update confirms their travel will be unaffected over the Victoria Day long weekend.”

Air Canada, the country’s largest carrier, said in a statement that it responded to the pilots’ strike vote mandate by adding capacity on key transcontinental routes to accommodate passengers fearful of possible travel disruptions. (Reporting by Allison Lampert; Editing by Cynthia Osterman and Peter Cooney)